A PTC element or a PTC thermistor, which is also called a positive temperature coefficient thermistor, exhibits a behavior characteristic in which at a specific temperature, its temperature rise due to phase transition to abruptly increase electric resistance.
Since electric resistance of the PTC element abruptly increases as described above, the PTC element is utilized as a switch for turning on/off power supply. Also, since the PTC element may reach a high temperature within a relatively short time and maintain the high temperature consistently, the PTC element is utilized as a heating body in a vehicle heater, a drier, a warmer, a medical instrument, a warmth mat, a heater or the like.
A PTC heater using the PTC element may include a heat diffusion fin which is generally attached to the PTC element to enhance heat diffusion efficiency of the PTC element. Also, if a power is applied to generate heat from the PTC element, the PTC heater allows air to pass through the PTC element and/or the heat diffusion fin and flow toward a target.
Commonly, a heater provided at a vehicle uses an engine room as a heat source. Here, a PTC heater may be applied as a pre-heater for preliminarily giving a heat beforehand before the temperature of the engine room rises to a suitable level.
Meanwhile, the interest on an electric vehicle has recently increased due to energy efficiency, environment-friendly issues or the like, and the electric vehicle does not have an engine room and thus a heater such as the PTC heater operated by an electric power source is mounted thereto.
Since an electric vehicle uses charged electric energy as a driving energy, electronic components having lower power consumption are generally loaded to the electric vehicle in order to ensure suitable mileage.
However, an existing PTC heater is generally developed as a universal heater, which is not optimized for vehicle environments such as vibrations caused by driving a vehicle, exposure to the outer environments, prevention of flooding or the like, and an optimal structure for energy efficiency is not applied to the existing PTC heater.
In particular, for the electric vehicle, the energy efficiency is a most important issue. However, an existing PTC heater is just configured to generate heat with a power applied thereto without classifying and individually controlling heating areas (for example, a driver seat and a passenger seat), but the existing PTC heater is just capable of generating heat with respect to a single target, which may waste energy unnecessarily.
Korean Unexamined Patent Publication No. 2012-0041322 and Korean Unexamined Patent Publication No. 2015-0078826 disclose a PTC heater mounted to a vehicle, but these documents just disclose a physical structure, arrangement or the like for enhancing thermal efficiency. Even though they have some disclosure in relation to temperature control for a driver seat and a passenger seat, this temperature control is performed using a PWM control signal, and thus there is a limit in perfectly classifying seating sectors and independently controlling the heating sectors within a limited space of a vehicle just through simple structure improvement.